"Sainichi" could probably be translated as "day of the temple visit", although 賽 is a rather uncommon kanji and I reckon 賽日 is only used in this specific context.There are two days each year that are considered as "Enma Sainichi".16th of January
16th of JulysighTo think I only get two days off a year...That being said, I reckon it's been quite some time since the last time I slept this well...
They say it's a day in which the lid of the cauldron of hell is said to be open, and ghosts and the souls of the deceased are granted some reprieve from the pains of hell!